Octacontagon Number | C # program for above approach ; Finding the nth octacontagon Number ; Driver Code
using System ; class GFG { static int octacontagonNum ( int n ) { return ( 78 * n * n - 76 * n ) / 2 ; } public static void Main ( ) { int n = 3 ; Console . Write ( "3rd ▁ octacontagon ▁ Number ▁ is ▁ = ▁ " + octacontagonNum ( n ) ) ; } }